The invention disclosed and claimed herein relates generally to movable, self-assembling, self-elevating artificial structures designed to provide a stable, elevated work island or platform from which desired operations may be conducted over water. In certain fields of work, such structures are referred to as xe2x80x9cjack-upxe2x80x9d rigs or platforms. With more particularity, the invention disclosed and claimed herein relates to a platform composed of a plurality of independently buoyant, modular hull components each of which is navigable through waterways of limited width, depth and/or overhead clearance; each of which is capable of being facilely coupled together with other hull components at desired work locations to form a larger self-elevating work platform; wherein said work platform may be subsequently, either as an integral unit or by disassembly of the modular hull components, buoyantly navigated to other work locations.
Particularly in the field of oil and gas exploration and production, xe2x80x9cjack-upxe2x80x9d structures of various designs are well known. Though such structures have utility beyond oil and gas exploration and production (such as facilities for navigational beacons, weather stations, offshore mooring facilities, and as work platforms from which above-water and underwater construction and/or repairs may be conducted) they are most frequently used for earth boring, and production of fluid minerals from earth bores, located below water of xe2x80x9cmediumxe2x80x9d depth. By water of xe2x80x9cmediumxe2x80x9d depth it should be understood that submersible barges are usually used in very shallow (approximately less than 15 feet) water, xe2x80x9cposted bargesxe2x80x9d in waters of slightly greater depth (approximately less than 25 feet) and various floatable or permanent structures used in deep (approximately over 250 feet) water. It is to be understood, however, that jackup structures (in particular, the structure of the present invention) may be used in waters of very shallow depth, for example on the order of 8 feet deep.
Thus, without limiting the use of jackup structures to other depths, it is in water depths of approximately 8 feet to 250 feet deep, that jack-up structures find their greatest utility. Prior art teaches that such structures consist of a single buoyant hull, a plurality (usually three) of legs, jacking mechanisms that can raise or lower the legs as required and equipment designed to support the operations to be conducted at the work location. Such structures are typically buoyantly navigated on water, typically by tow, to a work location, after which the legs are lowered to the bottom, followed by continued jacking until the hull is a suitable distance (usually called an xe2x80x9cair gapxe2x80x9d) above the surface of the water. Typically from such elevated position desired operations are conducted, and when complete, the jack-up can be re-mobilized by jacking-down until the hull is re-floated, the legs lifted from the bottom and the unit navigated on water, typically by towing, to subsequent work locations.
However, in addition to the depth limitations suggested above, prior art jack-ups have other limitations. If the platform of the jack-up is relatively small, the distance between the legs supporting the platform is relatively small, and such a platform cannot be safely used in deep water (as the jack up is thereby unstable and likely to topple over). If, on the other hand, the platform of the jack-up is large (and therefore the legs can be sufficiently spaced apart to support operations over deeper water) such platform is of substantial beam and thus cannot be moved through narrow waterways to certain bodies of water.
By way of example, one body of water which is more than sufficient size to accommodate large jack-ups, and where such structures are greatly needed for exploration and/or production of oil and gas, is the Caspian Sea. However, such structures cannot be navigated to the Caspian Sea at the present time due to the relatively narrow width, relatively low height and relatively shallow draft limitations of waterways leading thereto. In addition, the shipyard facilities located on the Caspian Sea are inadequate for construction of such structures on-site. Even if such structures were constructed on the Caspian Sea, they could not be quickly or economically moved out of the Caspian Sea through presently existing water ways, should that become necessary.
Accordingly, and the Caspian Sea is but one example, there is a great need for a jack-up structure of substantial size (that is, the horizontal distance between supporting legs is substantial, thereby safely supporting a jack-up in water of substantial depth) which can be brought to a work body of water through relatively narrow waterways leading thereto. Without limitation (because the invention disclosed and claimed herein can also be used in almost any environment where currently existing jack-ups are used) the present invention is directed towards provision of a self-elevating (jack-up) work platform of substantial size, which is comprised of a plurality of modular buoyant components designed to be navigated through waterways of limited width, height and/or draft, and is facilely self-assembling on a work body of water. The design of the present invention also permits its fabrication in a large number of shipyards not having sufficient water depth or width to build a conventional jack-up unit, since the present invention comprising multiple, relatively narrow and shallow draft hull components can be fabricated in shipyards with limited water depth and width capabilities.
The present invention is directed to a movable, self-elevating (jack-up), artificial work island or platform composed of a plurality of relatively narrow, independently buoyant, modular and self-assembling hull components, each of said hull components capable of independent navigation through relatively narrow waterways and thereafter being facilely coupled together at a work location to form a larger, self-elevating, work platform. Said invention is primarily characterized as comprising a plurality of modular hull components designed to be coupled together at a work location to form a larger self-elevating work platform. Each modular hull component is independently buoyant and is therefore capable of navigating, typically under tow, as a separate vessel. Said hull components are of narrow beam so that they may be buoyantly navigated through narrow waterways. Said hull components are preferably elongated (having a length in excess of their narrow beam) so as to minimize the number of hull components required to form a work platform of desired size, and to maximize the distance between the legs supporting the assembled work platform. They may also be of relatively low height and of shallow draft where overhead clearances and depth of the narrow waterways are also limited.
When reaching a work location, the modular hull components are designed to be self-assembling (facilely coupled together on a work body of water) to form a work platform having a substantially larger beam than the individual hull components. After assembly, typical leg means and jacking means are employed to elevate and lower the assembled work island as desired. The assembled work platform is itself buoyant and may be moved to subsequent work locations over waters sufficient to accommodate the beams of the assembled work platform. Coupling of the individual hull components together may be facilely reversible or substantially permanent. Whatever means of coupling and assembly is employed, the modular hull components of the work platform may be facilely and economically de-coupled, on the work body of water, and subsequently navigated as independent modules through either narrow waterways or over open water.
The principal object of the present invention is to provide an improved mobile, self-elevating work island or platform. More particularly an object of the invention is to provide a mobile, self-elevating work island composed of a plurality of assembled modular hull components each of which is of narrow beam, is independently buoyant, and is therefore capable of being independently navigated, as a vessel, typically by tow, through relatively narrow waterways. Another object of the invention is to provide a plurality of independently buoyant modular hull components which are capable of being interconnected with other hull components to form a work platform which is larger than said modular hull components. Yet another object of the invention is to provide an assembled self-elevating work platform which is itself capable of being buoyantly navigated as an integral unit, typically by tow, over waters of sufficient width to accommodate the beam of the assembled work platform.
A platform composed of narrow hull components which is, while disassembled, capable of being navigated through narrow waterways, forms another object of the invention. An artificial work island composed of such hull components may also be, while disassembled, more facilely navigated over open water than a typical work platform (of substantial beam and roughly equal length); therefore yet another object of the invention is to provide for such a work platform. Another object is to provide a work platform which, when disassembled, may be efficiently transported over waterbodies on heavy lift vessels or xe2x80x9cdry towxe2x80x9d vessels.